Correlation of mRNA and protein

Hi
I like to know whether mRNA and Protein expression are always correlating. During time point studies, at 3 different time points, the first and last points of mrna expression are correlating with the protein in immunohistochemistry. but at the 2nd time point, the mrna is low but protein is the same

Is it the feed back effect due to retaining the proteins without degradation so that the mrna is downregulated. Are there any other reasons?

mRNA levels may not always correlate with the levels of protein and dependent upon many fators for e.g
human globin mRNA is highly stable and compensates for the synthesis of hemoglobin through out the life span of RBC (120 days). While the mRNA levels remain same in this case, level of protein varies.
In same way it is dependent upon
1. Rate of transcrption
2. stability of mRNA
3. Stability of protein
4. Feedback/ Feedforward systems
5. T1/2 of mRNA and Protein in circulation
and many more